1 // SPDX-License-Identifier: GPL-2.0-only
3 * linux/fs/nfs/direct.c
5 * Copyright (C) 2003 by Chuck Lever <cel@netapp.com>
7 * High-performance uncached I/O for the Linux NFS client
9 * There are important applications whose performance or correctness
10 * depends on uncached access to file data. Database clusters
11 * (multiple copies of the same instance running on separate hosts)
12 * implement their own cache coherency protocol that subsumes file
13 * system cache protocols. Applications that process datasets
14 * considerably larger than the client's memory do not always benefit
15 * from a local cache. A streaming video server, for instance, has no
16 * need to cache the contents of a file.
18 * When an application requests uncached I/O, all read and write requests
19 * are made directly to the server; data stored or fetched via these
20 * requests is not cached in the Linux page cache. The client does not
21 * correct unaligned requests from applications. All requested bytes are
22 * held on permanent storage before a direct write system call returns to
25 * Solaris implements an uncached I/O facility called directio() that
26 * is used for backups and sequential I/O to very large files. Solaris
27 * also supports uncaching whole NFS partitions with "-o forcedirectio,"
28 * an undocumented mount option.
30 * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with
31 * help from Andrew Morton.
33 * 18 Dec 2001 Initial implementation for 2.4 --cel
34 * 08 Jul 2002 Version for 2.4.19, with bug fixes --trondmy
35 * 08 Jun 2003 Port to 2.5 APIs --cel
36 * 31 Mar 2004 Handle direct I/O without VFS support --cel
37 * 15 Sep 2004 Parallel async reads --cel
38 * 04 May 2005 support O_DIRECT with aio --cel
42 #include <linux/errno.h>
43 #include <linux/sched.h>
44 #include <linux/kernel.h>
45 #include <linux/file.h>
46 #include <linux/pagemap.h>
47 #include <linux/kref.h>
48 #include <linux/slab.h>
49 #include <linux/task_io_accounting_ops.h>
50 #include <linux/module.h>
52 #include <linux/nfs_fs.h>
53 #include <linux/nfs_page.h>
54 #include <linux/sunrpc/clnt.h>
56 #include <linux/uaccess.h>
57 #include <linux/atomic.h>
63 #define NFSDBG_FACILITY NFSDBG_VFS
65 static struct kmem_cache
*nfs_direct_cachep
;
68 * This represents a set of asynchronous requests that we're waiting on
70 struct nfs_direct_mirror
{
74 struct nfs_direct_req
{
75 struct kref kref
; /* release manager */
78 struct nfs_open_context
*ctx
; /* file open context info */
79 struct nfs_lock_context
*l_ctx
; /* Lock context info */
80 struct kiocb
* iocb
; /* controlling i/o request */
81 struct inode
* inode
; /* target file of i/o */
83 /* completion state */
84 atomic_t io_count
; /* i/os we're waiting for */
85 spinlock_t lock
; /* protect completion state */
87 struct nfs_direct_mirror mirrors
[NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX
];
90 loff_t io_start
; /* Start offset for I/O */
91 ssize_t count
, /* bytes actually processed */
92 max_count
, /* max expected count */
93 bytes_left
, /* bytes left to be sent */
94 error
; /* any reported error */
95 struct completion completion
; /* wait for i/o completion */
98 struct nfs_mds_commit_info mds_cinfo
; /* Storage for cinfo */
99 struct pnfs_ds_commit_info ds_cinfo
; /* Storage for cinfo */
100 struct work_struct work
;
103 #define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */
104 #define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */
106 #define NFS_ODIRECT_SHOULD_DIRTY (3) /* dirty user-space page after read */
107 struct nfs_writeverf verf
; /* unstable write verifier */
110 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops
;
111 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops
;
112 static void nfs_direct_write_complete(struct nfs_direct_req
*dreq
);
113 static void nfs_direct_write_schedule_work(struct work_struct
*work
);
115 static inline void get_dreq(struct nfs_direct_req
*dreq
)
117 atomic_inc(&dreq
->io_count
);
120 static inline int put_dreq(struct nfs_direct_req
*dreq
)
122 return atomic_dec_and_test(&dreq
->io_count
);
126 nfs_direct_good_bytes(struct nfs_direct_req
*dreq
, struct nfs_pgio_header
*hdr
)
131 WARN_ON_ONCE(dreq
->count
>= dreq
->max_count
);
133 if (dreq
->mirror_count
== 1) {
134 dreq
->mirrors
[hdr
->pgio_mirror_idx
].count
+= hdr
->good_bytes
;
135 dreq
->count
+= hdr
->good_bytes
;
137 /* mirrored writes */
138 count
= dreq
->mirrors
[hdr
->pgio_mirror_idx
].count
;
139 if (count
+ dreq
->io_start
< hdr
->io_start
+ hdr
->good_bytes
) {
140 count
= hdr
->io_start
+ hdr
->good_bytes
- dreq
->io_start
;
141 dreq
->mirrors
[hdr
->pgio_mirror_idx
].count
= count
;
143 /* update the dreq->count by finding the minimum agreed count from all
145 count
= dreq
->mirrors
[0].count
;
147 for (i
= 1; i
< dreq
->mirror_count
; i
++)
148 count
= min(count
, dreq
->mirrors
[i
].count
);
155 * nfs_direct_select_verf - select the right verifier
156 * @dreq - direct request possibly spanning multiple servers
157 * @ds_clp - nfs_client of data server or NULL if MDS / non-pnfs
158 * @commit_idx - commit bucket index for the DS
160 * returns the correct verifier to use given the role of the server
162 static struct nfs_writeverf
*
163 nfs_direct_select_verf(struct nfs_direct_req
*dreq
,
164 struct nfs_client
*ds_clp
,
167 struct nfs_writeverf
*verfp
= &dreq
->verf
;
169 #ifdef CONFIG_NFS_V4_1
171 * pNFS is in use, use the DS verf except commit_through_mds is set
172 * for layout segment where nbuckets is zero.
174 if (ds_clp
&& dreq
->ds_cinfo
.nbuckets
> 0) {
175 if (commit_idx
>= 0 && commit_idx
< dreq
->ds_cinfo
.nbuckets
)
176 verfp
= &dreq
->ds_cinfo
.buckets
[commit_idx
].direct_verf
;
186 * nfs_direct_set_hdr_verf - set the write/commit verifier
187 * @dreq - direct request possibly spanning multiple servers
188 * @hdr - pageio header to validate against previously seen verfs
190 * Set the server's (MDS or DS) "seen" verifier
192 static void nfs_direct_set_hdr_verf(struct nfs_direct_req
*dreq
,
193 struct nfs_pgio_header
*hdr
)
195 struct nfs_writeverf
*verfp
;
197 verfp
= nfs_direct_select_verf(dreq
, hdr
->ds_clp
, hdr
->ds_commit_idx
);
198 WARN_ON_ONCE(verfp
->committed
>= 0);
199 memcpy(verfp
, &hdr
->verf
, sizeof(struct nfs_writeverf
));
200 WARN_ON_ONCE(verfp
->committed
< 0);
203 static int nfs_direct_cmp_verf(const struct nfs_writeverf
*v1
,
204 const struct nfs_writeverf
*v2
)
206 return nfs_write_verifier_cmp(&v1
->verifier
, &v2
->verifier
);
210 * nfs_direct_cmp_hdr_verf - compare verifier for pgio header
211 * @dreq - direct request possibly spanning multiple servers
212 * @hdr - pageio header to validate against previously seen verf
214 * set the server's "seen" verf if not initialized.
215 * returns result of comparison between @hdr->verf and the "seen"
216 * verf of the server used by @hdr (DS or MDS)
218 static int nfs_direct_set_or_cmp_hdr_verf(struct nfs_direct_req
*dreq
,
219 struct nfs_pgio_header
*hdr
)
221 struct nfs_writeverf
*verfp
;
223 verfp
= nfs_direct_select_verf(dreq
, hdr
->ds_clp
, hdr
->ds_commit_idx
);
224 if (verfp
->committed
< 0) {
225 nfs_direct_set_hdr_verf(dreq
, hdr
);
228 return nfs_direct_cmp_verf(verfp
, &hdr
->verf
);
232 * nfs_direct_cmp_commit_data_verf - compare verifier for commit data
233 * @dreq - direct request possibly spanning multiple servers
234 * @data - commit data to validate against previously seen verf
236 * returns result of comparison between @data->verf and the verf of
237 * the server used by @data (DS or MDS)
239 static int nfs_direct_cmp_commit_data_verf(struct nfs_direct_req
*dreq
,
240 struct nfs_commit_data
*data
)
242 struct nfs_writeverf
*verfp
;
244 verfp
= nfs_direct_select_verf(dreq
, data
->ds_clp
,
245 data
->ds_commit_index
);
247 /* verifier not set so always fail */
248 if (verfp
->committed
< 0)
251 return nfs_direct_cmp_verf(verfp
, &data
->verf
);
255 * nfs_direct_IO - NFS address space operation for direct I/O
256 * @iocb: target I/O control block
259 * The presence of this routine in the address space ops vector means
260 * the NFS client supports direct I/O. However, for most direct IO, we
261 * shunt off direct read and write requests before the VFS gets them,
262 * so this method is only ever called for swap.
264 ssize_t
nfs_direct_IO(struct kiocb
*iocb
, struct iov_iter
*iter
)
266 struct inode
*inode
= iocb
->ki_filp
->f_mapping
->host
;
268 /* we only support swap file calling nfs_direct_IO */
269 if (!IS_SWAPFILE(inode
))
272 VM_BUG_ON(iov_iter_count(iter
) != PAGE_SIZE
);
274 if (iov_iter_rw(iter
) == READ
)
275 return nfs_file_direct_read(iocb
, iter
);
276 return nfs_file_direct_write(iocb
, iter
);
279 static void nfs_direct_release_pages(struct page
**pages
, unsigned int npages
)
282 for (i
= 0; i
< npages
; i
++)
286 void nfs_init_cinfo_from_dreq(struct nfs_commit_info
*cinfo
,
287 struct nfs_direct_req
*dreq
)
289 cinfo
->inode
= dreq
->inode
;
290 cinfo
->mds
= &dreq
->mds_cinfo
;
291 cinfo
->ds
= &dreq
->ds_cinfo
;
293 cinfo
->completion_ops
= &nfs_direct_commit_completion_ops
;
296 static inline void nfs_direct_setup_mirroring(struct nfs_direct_req
*dreq
,
297 struct nfs_pageio_descriptor
*pgio
,
298 struct nfs_page
*req
)
300 int mirror_count
= 1;
302 if (pgio
->pg_ops
->pg_get_mirror_count
)
303 mirror_count
= pgio
->pg_ops
->pg_get_mirror_count(pgio
, req
);
305 dreq
->mirror_count
= mirror_count
;
308 static inline struct nfs_direct_req
*nfs_direct_req_alloc(void)
310 struct nfs_direct_req
*dreq
;
312 dreq
= kmem_cache_zalloc(nfs_direct_cachep
, GFP_KERNEL
);
316 kref_init(&dreq
->kref
);
317 kref_get(&dreq
->kref
);
318 init_completion(&dreq
->completion
);
319 INIT_LIST_HEAD(&dreq
->mds_cinfo
.list
);
320 dreq
->verf
.committed
= NFS_INVALID_STABLE_HOW
; /* not set yet */
321 INIT_WORK(&dreq
->work
, nfs_direct_write_schedule_work
);
322 dreq
->mirror_count
= 1;
323 spin_lock_init(&dreq
->lock
);
328 static void nfs_direct_req_free(struct kref
*kref
)
330 struct nfs_direct_req
*dreq
= container_of(kref
, struct nfs_direct_req
, kref
);
332 nfs_free_pnfs_ds_cinfo(&dreq
->ds_cinfo
);
333 if (dreq
->l_ctx
!= NULL
)
334 nfs_put_lock_context(dreq
->l_ctx
);
335 if (dreq
->ctx
!= NULL
)
336 put_nfs_open_context(dreq
->ctx
);
337 kmem_cache_free(nfs_direct_cachep
, dreq
);
340 static void nfs_direct_req_release(struct nfs_direct_req
*dreq
)
342 kref_put(&dreq
->kref
, nfs_direct_req_free
);
345 ssize_t
nfs_dreq_bytes_left(struct nfs_direct_req
*dreq
)
347 return dreq
->bytes_left
;
349 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left
);
352 * Collects and returns the final error value/byte-count.
354 static ssize_t
nfs_direct_wait(struct nfs_direct_req
*dreq
)
356 ssize_t result
= -EIOCBQUEUED
;
358 /* Async requests don't wait here */
362 result
= wait_for_completion_killable(&dreq
->completion
);
365 result
= dreq
->count
;
366 WARN_ON_ONCE(dreq
->count
< 0);
369 result
= dreq
->error
;
372 return (ssize_t
) result
;
376 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
377 * the iocb is still valid here if this is a synchronous request.
379 static void nfs_direct_complete(struct nfs_direct_req
*dreq
)
381 struct inode
*inode
= dreq
->inode
;
383 inode_dio_end(inode
);
386 long res
= (long) dreq
->error
;
387 if (dreq
->count
!= 0) {
388 res
= (long) dreq
->count
;
389 WARN_ON_ONCE(dreq
->count
< 0);
391 dreq
->iocb
->ki_complete(dreq
->iocb
, res
, 0);
394 complete(&dreq
->completion
);
396 nfs_direct_req_release(dreq
);
399 static void nfs_direct_read_completion(struct nfs_pgio_header
*hdr
)
401 unsigned long bytes
= 0;
402 struct nfs_direct_req
*dreq
= hdr
->dreq
;
404 if (test_bit(NFS_IOHDR_REDO
, &hdr
->flags
))
407 spin_lock(&dreq
->lock
);
408 if (test_bit(NFS_IOHDR_ERROR
, &hdr
->flags
) && (hdr
->good_bytes
== 0))
409 dreq
->error
= hdr
->error
;
411 nfs_direct_good_bytes(dreq
, hdr
);
413 spin_unlock(&dreq
->lock
);
415 while (!list_empty(&hdr
->pages
)) {
416 struct nfs_page
*req
= nfs_list_entry(hdr
->pages
.next
);
417 struct page
*page
= req
->wb_page
;
419 if (!PageCompound(page
) && bytes
< hdr
->good_bytes
&&
420 (dreq
->flags
== NFS_ODIRECT_SHOULD_DIRTY
))
421 set_page_dirty(page
);
422 bytes
+= req
->wb_bytes
;
423 nfs_list_remove_request(req
);
424 nfs_release_request(req
);
428 nfs_direct_complete(dreq
);
432 static void nfs_read_sync_pgio_error(struct list_head
*head
, int error
)
434 struct nfs_page
*req
;
436 while (!list_empty(head
)) {
437 req
= nfs_list_entry(head
->next
);
438 nfs_list_remove_request(req
);
439 nfs_release_request(req
);
443 static void nfs_direct_pgio_init(struct nfs_pgio_header
*hdr
)
448 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops
= {
449 .error_cleanup
= nfs_read_sync_pgio_error
,
450 .init_hdr
= nfs_direct_pgio_init
,
451 .completion
= nfs_direct_read_completion
,
455 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
456 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
457 * bail and stop sending more reads. Read length accounting is
458 * handled automatically by nfs_direct_read_result(). Otherwise, if
459 * no requests have been sent, just return an error.
462 static ssize_t
nfs_direct_read_schedule_iovec(struct nfs_direct_req
*dreq
,
463 struct iov_iter
*iter
,
466 struct nfs_pageio_descriptor desc
;
467 struct inode
*inode
= dreq
->inode
;
468 ssize_t result
= -EINVAL
;
469 size_t requested_bytes
= 0;
470 size_t rsize
= max_t(size_t, NFS_SERVER(inode
)->rsize
, PAGE_SIZE
);
472 nfs_pageio_init_read(&desc
, dreq
->inode
, false,
473 &nfs_direct_read_completion_ops
);
476 inode_dio_begin(inode
);
478 while (iov_iter_count(iter
)) {
479 struct page
**pagevec
;
484 result
= iov_iter_get_pages_alloc(iter
, &pagevec
,
490 iov_iter_advance(iter
, bytes
);
491 npages
= (result
+ pgbase
+ PAGE_SIZE
- 1) / PAGE_SIZE
;
492 for (i
= 0; i
< npages
; i
++) {
493 struct nfs_page
*req
;
494 unsigned int req_len
= min_t(size_t, bytes
, PAGE_SIZE
- pgbase
);
495 /* XXX do we need to do the eof zeroing found in async_filler? */
496 req
= nfs_create_request(dreq
->ctx
, pagevec
[i
],
499 result
= PTR_ERR(req
);
502 req
->wb_index
= pos
>> PAGE_SHIFT
;
503 req
->wb_offset
= pos
& ~PAGE_MASK
;
504 if (!nfs_pageio_add_request(&desc
, req
)) {
505 result
= desc
.pg_error
;
506 nfs_release_request(req
);
511 requested_bytes
+= req_len
;
513 dreq
->bytes_left
-= req_len
;
515 nfs_direct_release_pages(pagevec
, npages
);
521 nfs_pageio_complete(&desc
);
524 * If no bytes were started, return the error, and let the
525 * generic layer handle the completion.
527 if (requested_bytes
== 0) {
528 inode_dio_end(inode
);
529 nfs_direct_req_release(dreq
);
530 return result
< 0 ? result
: -EIO
;
534 nfs_direct_complete(dreq
);
535 return requested_bytes
;
539 * nfs_file_direct_read - file direct read operation for NFS files
540 * @iocb: target I/O control block
541 * @iter: vector of user buffers into which to read data
543 * We use this function for direct reads instead of calling
544 * generic_file_aio_read() in order to avoid gfar's check to see if
545 * the request starts before the end of the file. For that check
546 * to work, we must generate a GETATTR before each direct read, and
547 * even then there is a window between the GETATTR and the subsequent
548 * READ where the file size could change. Our preference is simply
549 * to do all reads the application wants, and the server will take
550 * care of managing the end of file boundary.
552 * This function also eliminates unnecessarily updating the file's
553 * atime locally, as the NFS server sets the file's atime, and this
554 * client must read the updated atime from the server back into its
557 ssize_t
nfs_file_direct_read(struct kiocb
*iocb
, struct iov_iter
*iter
)
559 struct file
*file
= iocb
->ki_filp
;
560 struct address_space
*mapping
= file
->f_mapping
;
561 struct inode
*inode
= mapping
->host
;
562 struct nfs_direct_req
*dreq
;
563 struct nfs_lock_context
*l_ctx
;
564 ssize_t result
= -EINVAL
, requested
;
565 size_t count
= iov_iter_count(iter
);
566 nfs_add_stats(mapping
->host
, NFSIOS_DIRECTREADBYTES
, count
);
568 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
569 file
, count
, (long long) iocb
->ki_pos
);
575 task_io_account_read(count
);
578 dreq
= nfs_direct_req_alloc();
583 dreq
->bytes_left
= dreq
->max_count
= count
;
584 dreq
->io_start
= iocb
->ki_pos
;
585 dreq
->ctx
= get_nfs_open_context(nfs_file_open_context(iocb
->ki_filp
));
586 l_ctx
= nfs_get_lock_context(dreq
->ctx
);
588 result
= PTR_ERR(l_ctx
);
592 if (!is_sync_kiocb(iocb
))
595 if (iter_is_iovec(iter
))
596 dreq
->flags
= NFS_ODIRECT_SHOULD_DIRTY
;
598 nfs_start_io_direct(inode
);
600 NFS_I(inode
)->read_io
+= count
;
601 requested
= nfs_direct_read_schedule_iovec(dreq
, iter
, iocb
->ki_pos
);
603 nfs_end_io_direct(inode
);
606 result
= nfs_direct_wait(dreq
);
609 iocb
->ki_pos
+= result
;
611 iov_iter_revert(iter
, requested
);
617 nfs_direct_req_release(dreq
);
623 nfs_direct_write_scan_commit_list(struct inode
*inode
,
624 struct list_head
*list
,
625 struct nfs_commit_info
*cinfo
)
627 mutex_lock(&NFS_I(cinfo
->inode
)->commit_mutex
);
628 #ifdef CONFIG_NFS_V4_1
629 if (cinfo
->ds
!= NULL
&& cinfo
->ds
->nwritten
!= 0)
630 NFS_SERVER(inode
)->pnfs_curr_ld
->recover_commit_reqs(list
, cinfo
);
632 nfs_scan_commit_list(&cinfo
->mds
->list
, list
, cinfo
, 0);
633 mutex_unlock(&NFS_I(cinfo
->inode
)->commit_mutex
);
636 static void nfs_direct_write_reschedule(struct nfs_direct_req
*dreq
)
638 struct nfs_pageio_descriptor desc
;
639 struct nfs_page
*req
, *tmp
;
641 struct nfs_commit_info cinfo
;
645 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
646 nfs_direct_write_scan_commit_list(dreq
->inode
, &reqs
, &cinfo
);
649 dreq
->verf
.committed
= NFS_INVALID_STABLE_HOW
;
650 nfs_clear_pnfs_ds_commit_verifiers(&dreq
->ds_cinfo
);
651 for (i
= 0; i
< dreq
->mirror_count
; i
++)
652 dreq
->mirrors
[i
].count
= 0;
655 nfs_pageio_init_write(&desc
, dreq
->inode
, FLUSH_STABLE
, false,
656 &nfs_direct_write_completion_ops
);
659 req
= nfs_list_entry(reqs
.next
);
660 nfs_direct_setup_mirroring(dreq
, &desc
, req
);
661 if (desc
.pg_error
< 0) {
662 list_splice_init(&reqs
, &failed
);
666 list_for_each_entry_safe(req
, tmp
, &reqs
, wb_list
) {
667 /* Bump the transmission count */
669 if (!nfs_pageio_add_request(&desc
, req
)) {
670 nfs_list_move_request(req
, &failed
);
671 spin_lock(&cinfo
.inode
->i_lock
);
673 if (desc
.pg_error
< 0)
674 dreq
->error
= desc
.pg_error
;
677 spin_unlock(&cinfo
.inode
->i_lock
);
679 nfs_release_request(req
);
681 nfs_pageio_complete(&desc
);
684 while (!list_empty(&failed
)) {
685 req
= nfs_list_entry(failed
.next
);
686 nfs_list_remove_request(req
);
687 nfs_unlock_and_release_request(req
);
691 nfs_direct_write_complete(dreq
);
694 static void nfs_direct_commit_complete(struct nfs_commit_data
*data
)
696 struct nfs_direct_req
*dreq
= data
->dreq
;
697 struct nfs_commit_info cinfo
;
698 struct nfs_page
*req
;
699 int status
= data
->task
.tk_status
;
701 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
702 if (status
< 0 || nfs_direct_cmp_commit_data_verf(dreq
, data
))
703 dreq
->flags
= NFS_ODIRECT_RESCHED_WRITES
;
705 while (!list_empty(&data
->pages
)) {
706 req
= nfs_list_entry(data
->pages
.next
);
707 nfs_list_remove_request(req
);
708 if (dreq
->flags
== NFS_ODIRECT_RESCHED_WRITES
) {
710 * Despite the reboot, the write was successful,
714 /* Note the rewrite will go through mds */
715 nfs_mark_request_commit(req
, NULL
, &cinfo
, 0);
717 nfs_release_request(req
);
718 nfs_unlock_and_release_request(req
);
721 if (atomic_dec_and_test(&cinfo
.mds
->rpcs_out
))
722 nfs_direct_write_complete(dreq
);
725 static void nfs_direct_resched_write(struct nfs_commit_info
*cinfo
,
726 struct nfs_page
*req
)
728 struct nfs_direct_req
*dreq
= cinfo
->dreq
;
730 spin_lock(&dreq
->lock
);
731 dreq
->flags
= NFS_ODIRECT_RESCHED_WRITES
;
732 spin_unlock(&dreq
->lock
);
733 nfs_mark_request_commit(req
, NULL
, cinfo
, 0);
736 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops
= {
737 .completion
= nfs_direct_commit_complete
,
738 .resched_write
= nfs_direct_resched_write
,
741 static void nfs_direct_commit_schedule(struct nfs_direct_req
*dreq
)
744 struct nfs_commit_info cinfo
;
747 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
748 nfs_scan_commit(dreq
->inode
, &mds_list
, &cinfo
);
749 res
= nfs_generic_commit_list(dreq
->inode
, &mds_list
, 0, &cinfo
);
750 if (res
< 0) /* res == -ENOMEM */
751 nfs_direct_write_reschedule(dreq
);
754 static void nfs_direct_write_schedule_work(struct work_struct
*work
)
756 struct nfs_direct_req
*dreq
= container_of(work
, struct nfs_direct_req
, work
);
757 int flags
= dreq
->flags
;
761 case NFS_ODIRECT_DO_COMMIT
:
762 nfs_direct_commit_schedule(dreq
);
764 case NFS_ODIRECT_RESCHED_WRITES
:
765 nfs_direct_write_reschedule(dreq
);
768 nfs_zap_mapping(dreq
->inode
, dreq
->inode
->i_mapping
);
769 nfs_direct_complete(dreq
);
773 static void nfs_direct_write_complete(struct nfs_direct_req
*dreq
)
775 queue_work(nfsiod_workqueue
, &dreq
->work
); /* Calls nfs_direct_write_schedule_work */
778 static void nfs_direct_write_completion(struct nfs_pgio_header
*hdr
)
780 struct nfs_direct_req
*dreq
= hdr
->dreq
;
781 struct nfs_commit_info cinfo
;
782 bool request_commit
= false;
783 struct nfs_page
*req
= nfs_list_entry(hdr
->pages
.next
);
785 if (test_bit(NFS_IOHDR_REDO
, &hdr
->flags
))
788 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
790 spin_lock(&dreq
->lock
);
792 if (test_bit(NFS_IOHDR_ERROR
, &hdr
->flags
))
793 dreq
->error
= hdr
->error
;
794 if (dreq
->error
== 0) {
795 nfs_direct_good_bytes(dreq
, hdr
);
796 if (nfs_write_need_commit(hdr
)) {
797 if (dreq
->flags
== NFS_ODIRECT_RESCHED_WRITES
)
798 request_commit
= true;
799 else if (dreq
->flags
== 0) {
800 nfs_direct_set_hdr_verf(dreq
, hdr
);
801 request_commit
= true;
802 dreq
->flags
= NFS_ODIRECT_DO_COMMIT
;
803 } else if (dreq
->flags
== NFS_ODIRECT_DO_COMMIT
) {
804 request_commit
= true;
805 if (nfs_direct_set_or_cmp_hdr_verf(dreq
, hdr
))
807 NFS_ODIRECT_RESCHED_WRITES
;
811 spin_unlock(&dreq
->lock
);
813 while (!list_empty(&hdr
->pages
)) {
815 req
= nfs_list_entry(hdr
->pages
.next
);
816 nfs_list_remove_request(req
);
817 if (request_commit
) {
818 kref_get(&req
->wb_kref
);
819 nfs_mark_request_commit(req
, hdr
->lseg
, &cinfo
,
822 nfs_unlock_and_release_request(req
);
827 nfs_direct_write_complete(dreq
);
831 static void nfs_write_sync_pgio_error(struct list_head
*head
, int error
)
833 struct nfs_page
*req
;
835 while (!list_empty(head
)) {
836 req
= nfs_list_entry(head
->next
);
837 nfs_list_remove_request(req
);
838 nfs_unlock_and_release_request(req
);
842 static void nfs_direct_write_reschedule_io(struct nfs_pgio_header
*hdr
)
844 struct nfs_direct_req
*dreq
= hdr
->dreq
;
846 spin_lock(&dreq
->lock
);
847 if (dreq
->error
== 0) {
848 dreq
->flags
= NFS_ODIRECT_RESCHED_WRITES
;
849 /* fake unstable write to let common nfs resend pages */
850 hdr
->verf
.committed
= NFS_UNSTABLE
;
851 hdr
->good_bytes
= hdr
->args
.count
;
853 spin_unlock(&dreq
->lock
);
856 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops
= {
857 .error_cleanup
= nfs_write_sync_pgio_error
,
858 .init_hdr
= nfs_direct_pgio_init
,
859 .completion
= nfs_direct_write_completion
,
860 .reschedule_io
= nfs_direct_write_reschedule_io
,
865 * NB: Return the value of the first error return code. Subsequent
866 * errors after the first one are ignored.
869 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
870 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
871 * bail and stop sending more writes. Write length accounting is
872 * handled automatically by nfs_direct_write_result(). Otherwise, if
873 * no requests have been sent, just return an error.
875 static ssize_t
nfs_direct_write_schedule_iovec(struct nfs_direct_req
*dreq
,
876 struct iov_iter
*iter
,
879 struct nfs_pageio_descriptor desc
;
880 struct inode
*inode
= dreq
->inode
;
882 size_t requested_bytes
= 0;
883 size_t wsize
= max_t(size_t, NFS_SERVER(inode
)->wsize
, PAGE_SIZE
);
885 nfs_pageio_init_write(&desc
, inode
, FLUSH_COND_STABLE
, false,
886 &nfs_direct_write_completion_ops
);
889 inode_dio_begin(inode
);
891 NFS_I(inode
)->write_io
+= iov_iter_count(iter
);
892 while (iov_iter_count(iter
)) {
893 struct page
**pagevec
;
898 result
= iov_iter_get_pages_alloc(iter
, &pagevec
,
904 iov_iter_advance(iter
, bytes
);
905 npages
= (result
+ pgbase
+ PAGE_SIZE
- 1) / PAGE_SIZE
;
906 for (i
= 0; i
< npages
; i
++) {
907 struct nfs_page
*req
;
908 unsigned int req_len
= min_t(size_t, bytes
, PAGE_SIZE
- pgbase
);
910 req
= nfs_create_request(dreq
->ctx
, pagevec
[i
],
913 result
= PTR_ERR(req
);
917 nfs_direct_setup_mirroring(dreq
, &desc
, req
);
918 if (desc
.pg_error
< 0) {
919 nfs_free_request(req
);
920 result
= desc
.pg_error
;
924 nfs_lock_request(req
);
925 req
->wb_index
= pos
>> PAGE_SHIFT
;
926 req
->wb_offset
= pos
& ~PAGE_MASK
;
927 if (!nfs_pageio_add_request(&desc
, req
)) {
928 result
= desc
.pg_error
;
929 nfs_unlock_and_release_request(req
);
934 requested_bytes
+= req_len
;
936 dreq
->bytes_left
-= req_len
;
938 nfs_direct_release_pages(pagevec
, npages
);
943 nfs_pageio_complete(&desc
);
946 * If no bytes were started, return the error, and let the
947 * generic layer handle the completion.
949 if (requested_bytes
== 0) {
950 inode_dio_end(inode
);
951 nfs_direct_req_release(dreq
);
952 return result
< 0 ? result
: -EIO
;
956 nfs_direct_write_complete(dreq
);
957 return requested_bytes
;
961 * nfs_file_direct_write - file direct write operation for NFS files
962 * @iocb: target I/O control block
963 * @iter: vector of user buffers from which to write data
965 * We use this function for direct writes instead of calling
966 * generic_file_aio_write() in order to avoid taking the inode
967 * semaphore and updating the i_size. The NFS server will set
968 * the new i_size and this client must read the updated size
969 * back into its cache. We let the server do generic write
970 * parameter checking and report problems.
972 * We eliminate local atime updates, see direct read above.
974 * We avoid unnecessary page cache invalidations for normal cached
975 * readers of this file.
977 * Note that O_APPEND is not supported for NFS direct writes, as there
978 * is no atomic O_APPEND write facility in the NFS protocol.
980 ssize_t
nfs_file_direct_write(struct kiocb
*iocb
, struct iov_iter
*iter
)
982 ssize_t result
= -EINVAL
, requested
;
984 struct file
*file
= iocb
->ki_filp
;
985 struct address_space
*mapping
= file
->f_mapping
;
986 struct inode
*inode
= mapping
->host
;
987 struct nfs_direct_req
*dreq
;
988 struct nfs_lock_context
*l_ctx
;
991 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
992 file
, iov_iter_count(iter
), (long long) iocb
->ki_pos
);
994 result
= generic_write_checks(iocb
, iter
);
998 nfs_add_stats(mapping
->host
, NFSIOS_DIRECTWRITTENBYTES
, count
);
1001 end
= (pos
+ iov_iter_count(iter
) - 1) >> PAGE_SHIFT
;
1003 task_io_account_write(count
);
1006 dreq
= nfs_direct_req_alloc();
1010 dreq
->inode
= inode
;
1011 dreq
->bytes_left
= dreq
->max_count
= count
;
1012 dreq
->io_start
= pos
;
1013 dreq
->ctx
= get_nfs_open_context(nfs_file_open_context(iocb
->ki_filp
));
1014 l_ctx
= nfs_get_lock_context(dreq
->ctx
);
1015 if (IS_ERR(l_ctx
)) {
1016 result
= PTR_ERR(l_ctx
);
1019 dreq
->l_ctx
= l_ctx
;
1020 if (!is_sync_kiocb(iocb
))
1023 nfs_start_io_direct(inode
);
1025 requested
= nfs_direct_write_schedule_iovec(dreq
, iter
, pos
);
1027 if (mapping
->nrpages
) {
1028 invalidate_inode_pages2_range(mapping
,
1029 pos
>> PAGE_SHIFT
, end
);
1032 nfs_end_io_direct(inode
);
1034 if (requested
> 0) {
1035 result
= nfs_direct_wait(dreq
);
1037 requested
-= result
;
1038 iocb
->ki_pos
= pos
+ result
;
1039 /* XXX: should check the generic_write_sync retval */
1040 generic_write_sync(iocb
, result
);
1042 iov_iter_revert(iter
, requested
);
1047 nfs_direct_req_release(dreq
);
1053 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1056 int __init
nfs_init_directcache(void)
1058 nfs_direct_cachep
= kmem_cache_create("nfs_direct_cache",
1059 sizeof(struct nfs_direct_req
),
1060 0, (SLAB_RECLAIM_ACCOUNT
|
1063 if (nfs_direct_cachep
== NULL
)
1070 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1073 void nfs_destroy_directcache(void)
1075 kmem_cache_destroy(nfs_direct_cachep
);